The Pacific oyster, Magallana gigas (also known as Crassostrea gigas 1) is native to warm temperate regions, specifically the Northwest Pacific and Sea of Japan 2. The implications of model results are discussed in the context of wild oyster population management. However, external recruitment sources may be in competition with the wild population so that external recruitment is associated with a reduction in wild population density. Results indicate that long term persistence of wild oyster populations towards carrying capacity requires a high frequency of spawning events but that in the absence of spawning, external recruitment from farmed populations and other wild oyster populations may act to prevent extinction and increase population density. The impact of more frequent spawning events, external recruitment, and changes in carrying capacity on Pacific oyster density were simulated and compared under theoretical scenarios and two case studies in Southern England. This study applied an age-structured model, based on ordinary differential equations, to describe an oyster population under discrete temperature-related dynamics. Our understanding of the combined impact of the spawning frequency, external recruitment, and competition on wild population persistence is limited. Although correlation between the increasing abundance of Pacific oyster reefs in Northern European waters and climate change is documented, persistence of wild populations may also be influenced by external recruitment from farmed populations and other wild oyster populations, as well as on competition for resources with aquaculture sites. While reproduction is inhibited by cold waters, recent warm summer temperature has increased the frequency of spawning events. Persistence of wild Pacific oyster, Magallana gigas, also known as Crassostrea gigas, has been increasingly reported across Northern European waters in recent years.
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